Is it gonna seize??

[weasel]

Hi, ive just got a TZR 125 2RK on a K-plate, and ive put a sports exhaust on it (not sure of the make, but some of you may have seen it recently on Ebay) and a motorised powervalve kit, I am also led to believe that when i bought it, it had just been bored out 2mm, and what i was wondering was, with all these mods, is it likely to need re-jetting?

My dad knows a lot about 4-strokes, bot not 2 strokes, and he said to just leave well alone, and to just put an extra tiny splash of 2-stroke oil in the petral tank every time i fill it up just to be on the safe side.
But i thought id get a second opinion, so what do you think.

If it does, then what sort of size jet am i after, where could i get it from, how hard are they to change etc etc, because ive been told that some times the old one snaps off in the carb when trying to unscrew it, thus needing a new carb. and once you've changed it, does the needle need to be changed, to fit in the new sized one??

Any help would be good.

Cheers.
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Its still restricted officer.... Honest!

[R4nger]

Yes I would assume you do need to rejet it. As for the jet size I do not know however if you get it dyno'ed then that is the best bet.
Also put some intakes on aswell before the dyno to make your money worth while

[bish777]

If you cant afford a jet kit, an easy way to do it is to shim up your needles to richen the mixture. The shim only needs to be a mm or so to richen the mix. As a precaution add a 1/4 turn out to the pilot screw

The jets will be on the bottom of the carb its hidden from sight by the float bowl. They should unscrew without fuss. Note the size and get the next three sizes in a jet selection. Its then a case of changing the jets and needle heights to see what works best, chek the colour of the plugs and for and flat spots in the power curve that you can feel from the saddle.
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GSXR1100J

[ANDYNIC]

First of all you need to do a plug chop. Fit a new spark plug and take the bike to a stretch of road where you can thrash it. Run the bike on full throttle for about a mile and then cut the engine and pull over to the side of the road. Remove the spark plug and check the colour of the plug insulator. It should be light to medium brown in colour. If its very light or white then you could have a weak mixture and will need to increase the size of your main jet. What size you go to depends on what size you have in there at present. As jets are cheap i would buy 2 or 3 larger sizes remembering that it is better to go too big than too small. Get your jets here fantastic next day delivery https://www.fowlers.co.uk/. on no account should you add extra 2t oil to the petrol as this will actually weaken the mixture as the oil will replace petrol in the mix and thereby weaken it. Get yourself a haynes manual as the main jets are dead easy to replace and no they dont break off. To remove the main jet take off the carb float bowl, the main jet is the brass hexagonal fitting in the bottom of the carb next to the float. Hope this helps.

[binge]

Depending on how light or oiley your plug is, You may get away with just adjusting the Pilot screw.

Do a plug chop, if its white, Bring the Pilot screw out a turn. DO another plug chop. And go like that until you have a perfect plug.

[ANDYNIC]

The pilot screw controls how much air enters the pilot jet. This is the idle circuit and so only affects the idle or tickover. If its running weak you must change the main jet as this controls 3/4 to full throttle.